Weekly Outlook: December 16-22, 2019

We’ve got another week coming up with just about everything Mother Nature has to offer. Well, not quite everything, since we won’t have a warm day this week. To make up for it, we’ll have at least one day that is extremely cold. How’s that for a trade off?

The week starts off with high pressure in control. That means we’ll have some sunshine, less wind, and chilly temperatures today. The sunshine will not last long though, as clouds quickly move in ahead of our next system. That storm will move from the Tennessee Valley into the Mid-Atlantic states, passing south of New England on Tuesday. That’s about the only part of the storm that isn’t complicated.

Snow will develop across much of the region before daybreak on Tuesday. Yes, that means your morning commute on Tuesday will be even worse than normal. The snow should quickly change to rain along the South Coast. Away from the coast is where the problems start. Warmer air will move in aloft, with a change to sleet, freezing rain, and eventually plain rain expected to work its way northward on Tuesday. How quickly it moves northward, and how far north that changeover gets are still up in the air. Obviously, this has a major impact on how much snow accumulation we can expect. The other problem is, how long do some areas stay sleet or freezing rain, as this will have a significant impact on road conditions.

The High-Resolution NAM model shows the progression of the the precipitation and changeover line with the next storm system. Loop provided by WeatherBell.

So, how much snow can we expect before the changeover? Obviously, this is still a low-confidence forecast, despite the fact that it’s only a little more than a day away. Here’s what we’re thinking for now:

South Coast/Cape Cod: Little to no accumulation
Southeastern Massachusetts/Rhode Island (South and East of I-95): A coating to 2 inches.
Northern Rhode Island/MetroWest/North Shore/Merrimack Valley/NH Seacoast: 1-3″
Southern NH (Nashua-Manchester): 2-4″
Central NH (Concord-Lebanon): 4-7″

We’ll try to do an updated blog post late Monday, once we get a little more clarity on some of the details.

The GFS model is probably the closest to our thinking for snowfall amounts right now. Image provided by Weathermodels.com

So, everything winds down Tuesday evening, and then things improve on Wednesday, right? Not so much. A strong cold front will move across the region during the afternoon. This front may produce some snow showers or possibly snow squalls as it moves through during the afternoon and evening. Behind the front, some much colder air settles in for Wednesday night and Thursday. Now, it won’t be as cold as it was in the Dakotas and Minnesota, where it stayed below zero all day Saturday and Sunday (Can someone please explain why people choose to live in North Dakota?), but many parts of our area could stay below 20 all day on Thursday. When you fact in the wind, it will feel like it’s below zero, especially during the morning.

Heading out before daybreak Thursday? Bundle up, because wind chills will likely be below zero across the region, Image provided by WeatherBell.

High pressure builds in for Friday with dry weather, but it shouldn’t be as cold as Thursday. This brings us to the weekend. This is where things get questionable again. You may have heard some chatter online about a big snowstorm this weekend. Well, it’s a possibility, but then again, it’s also possible that the Patriots defense won’t give up a single point for the rest of the season. Most of the models have been signalling that there will be a potent storm system developing off the East Coast this weekend. Every now and then, one of the runs puts that storm right off of Cape Cod and shows the potential for a blizzard, sending all of the Facebook Forecasters into a frenzy. Of course, these same models have also shown the same storm moving off of Florida and then eastward across the Bahamas instead. Will there be a strong storm? Probably. Will it impact us? Probably not. However, one thing that may happen, is a weak system moving eastward bringing in a period of light snow sometime either late Saturday or Sunday. Given where the storm forms, it’s not really an Alberta Clipper, calling it a Dakota Dasher would probably be more accurate.

Nearly every run of the GFS over the past 5 days has had a strong storm near the East Coast this weekend. However, the placement and strength of the storm has varied on every run. Loop provided by Pivotal Weather.

If you’re really looking ahead, right now Christmas Eve and Christmas Day look dry and seasonably chilly.

Monday: Some sunshine early, then clouds thicken up. High 30-37.

Monday night: Cloudy with snow developing after midnight. Low 23-30.

Tuesday: Snow, changing to sleet, freezing rain, and plain rain from south to north. Areas north of the Mass Pike may never go to plain rain. High 27-34 north and west of Interstate 95, 34-41 south and east of Interstate 95.

Tuesday night: Precipitation ends in the evening, then skies clear out late at night. Low 21-28.

Wednesday: Morning sunshine, clouds return in the afternoon with some snow showers or squalls possible late in the day, becoming windy at night. High 30-37.

Thursday: Sunshine and a few clouds, breezy, and cold. High 17-24.

Friday: Partly to mostly sunny. High 22-29.

Saturday: Mostly cloudy, chance for some light snow or snow showers late in the day and at night. High 29-36.

Sunday: Partly to mostly cloudy with a chance of snow showers, especially in the morning. High 34-41.

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